×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Measurement of system short circuit level

Measurement of system short circuit level

Measurement of system short circuit level

(OP)
I heard that there is a method to measure the short circuit level at the bus. Technically it appears to be difficult and risky. I have not come across such measurements. Does anybody have clue on this?

RE: Measurement of system short circuit level

I have never done that in the direct sense. That would, indeed, be risky thumbsdown

But I have done a few estimates based on voltage drop during heavy starts. The results are in quite good accord (less than 10% error, mostly) with the results you get when using transformer and infeed impedance numbers.

You need a really heavy start so that the voltage drop can be measured with good accuracy. You also need to record the waveforms so you can find out phase relations and also make sure that switching transients and DC components have died out so that you use clean sine waves for the calculations.

I have seen low voltage voltage applied to the primary with a shorted secondary. The problem with that approach is that the upstream impedance usually differs a lot between the two supplies - the ordinary supply usually has a lot less impedance than the LV supply has.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Measurement of system short circuit level

Dear Krisys,

As Skogsgurra indicates, a think one can measure the short-circuit level (Scc) at a busbar just measuring the voltage change (deltaV) when switching a reactors or a capacitor bank (Mvar) onto that busbar.
So, the Scc will be numerically and approximately Scc = (V/deltaV)*Mvar.

Example: Capacitor bank = 20 Mvar, deltaV = 2%, V = 1pu
Scc = (1/0.02)*20 = 1,000 (MVA)

Best Regards,

Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&a...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources